Question

What is the output of the following snippet?

def f(x):
→if x == 0:
→→return 0
→return x + f(x - 1)

print(f(3))

Answer 1

The given Python code snippet recursively calculates the sum of natural numbers up to 3. The output of the function f(3) will be the number 6.

Step-by-step explanation:

The code provided is a Python function that calculates the sum of natural numbers up to a given number using recursion. Specifically, when f(3) is called, the function will recursively call itself with decremented values of x until x equals 0, at which point it returns 0 and unwinds the recursive calls, summing up the numbers as it returns.

The output will be computed as follows:

1. f(3) returns 3 + f(2)
2. f(2) returns 2 + f(1)
3. f(1) returns 1 + f(0)
4. f(0) returns 0

Adding these up, we get 3 + 2 + 1 + 0, which equals 6. Therefore, the output of the snippet when print(f(3)) is called will be 6.